Page 16 - Industrial Technology EXTRA 28th September 2020

ELECTRIC MOTORS...

Selecting the optimum motor

technology for an application

Selecting the motor for the motion portion of an application is rarely a
straightforward task, with different motor technologies all having

characteristics that impact on the design in different ways. Here, Dave
Beckstoffer of Portescap guides us through the factors to consider

s a design engineer, there is always higher speeds. In brushed DC motors, brush wear
excitement when you get to work on a increases at higher speeds, resulting in shorter life.
new product development. But, when it Steppers have a higher number of pole pairs so even
Acomes to motor selection, the challenge though they are electronically commutated, they are
can be difficult, with factors such as speed, torque, not designed to run at high speeds.
lifetime, mechanical envelope, noise, weight, cost
and precision all having an impact. Output torque
There are several technologies to consider, The next factor to consider is the output torque
including brushless DC, coreless DC and stepper requirement of the motion system, focusing on both
motors. So let’s work through the different the continuous torque and any peak torque for a
application parameters and look at how these limited time during operation. The different motor
impact on the choice of motor technology. technologies are characterised by different
maximum continuous output torque capabilities.
Motor speed Depending on the application, all three may be
One of the first factors to consider in a new product capable of delivering the required output torque.
development is the output speed requirement of the Alternatively, a gearhead could be added to increase
motion system. Based on their construction and the output torque capability of the motion system.
electronic commutation, brushless DC Note, however, that there is a corresponding
motors are most suited to run at reduction in output speed according to the ratio.

September 2020 • INDUSTRIAL TECHNOLOGY EXTRA • p16